Immunoglobulin A (IgA) is an antibody secreted most abundantly in mammals. It is secreted by IgA-producing cells in the lamina propria in the intestinal tract. IgA mainly functions to maintain homeostasis in the body through protecting the body from foreign pathogens contained in food or invading pathogenic bacteria and through maintaining the balance of intestinal bacterial flora (Non Patent Literatures 1 to 3). It is known that patients with IgA deficiency have a higher incidence of allergic disease and autoimmune disease (Non Patent Literature 4).
Interleukin-6 (IL-6), one of the cytokines produced by T cells and macrophages, plays a role in promoting hematopoiesis and differentiation into antibody-producing cells. On the other hand, when overproduced, it also acts to enhance inflammatory responses by, for example, causing chronic inflammation or autoimmune disease (Non Patent Literatures 5 and 6).
In view of the above, an attempt to modulate immune function by promoting IgA production and inhibiting the overproduction of IL-6 is useful for maintaining homeostasis in the body, preventing the development of allergy, and inhibiting inflammatory responses.
Meanwhile, γ-glutamyl-S-allylcysteine is a characteristic component of garlic. When garlic is cut, crushed, grated, or aged, this component is converted to water-soluble S-allylcysteine (here in below, abbreviated as SAC) by γ-glutamyltranspeptidase, an enzyme contained in garlic. In addition to SAC, there are other water-soluble compounds produced by such an enzymatic reaction, which are, for example, S-methylcysteine and S-1-propenylcysteine (Non Patent Literature 7).
There are numerous reports about the pharmacological action of SAC such as hepatoprotective effects (Non Patent Literature 8 and Patent Literature 1) and anti-colon cancer effects (Non Patent Literature 9). Further, S-methylcysteine has also been reported to have hepatoprotective effects (Patent Literature 2), cerebropathy improving effects (Patent Literature 1), and so on.
However, there has been no report about the pharmacological action of S-1-propenylcysteine, and it is totally unknown that S-1-propenylcysteine has immunomodulatory effects such as promoting effect of IgA production and inhibitory effect of IL-6 production.